1. Field of the Invention
The present invention relates to an ophthalmologic imaging apparatus and an ophthalmologic imaging method that captures a fundus of a subject's eye.
2. Description of the Related Art
Japanese Patent Application Laid-Open No. 2000-107133 discusses a fundus camera that can photograph a fundus by adequately shading a bright portion and a dark portion of the fundus within a photographing field of view, even if an exposure condition is unclear. This is a technique of causing a photographing light source to emit a strong light and a weak light alternately, when a fundus is subjected to fluorescence photography, since fluorescent intensity is significantly different between a thick blood vessel and a thin blood vessel.
Japanese Patent Application Laid-Open No. 2003-10134 discusses a fundus camera that can illuminate only an optic papilla with a visible light to adjust focusing in the optic papilla without contracting a pupil of a subject's eye.
However, Japanese Patent Application Laid-Open No. 2000-107133 does not discuss that a quantity of emitted light is adjusted according to a portion to be photographed, when the photographing light source is allowed to emit a strong light and a weak light. Further, the image obtained in Japanese Patent Application Laid-Open No. 2003-10134 is not a fundus image in which both the optic papilla and the portion other than the optic papilla are brought into focus, so that the image has an insufficient image quality for diagnosis.
It is considered here that an optic papilla and a macula are simultaneously photographed as a single fundus image, when the fundus is photographed. When the optic papilla is properly exposed, the macula is totally underexposed. On the contrary, when the macula is properly exposed, the optic papilla is totally overexposed. This is because the optic papilla is the brightest, and the macula is the darkest in the photographing field of view of the fundus, and a dynamic range of an image sensor is insufficient to simultaneously photograph both portions.
It is then considered the case in which the optic papilla is photographed with a visible light, while the macula is photographed with an infrared light, and then, both images are combined to form a fundus image. In this case, the combined image has an insufficient image quality for diagnosis, since these two images are not photographed with the same light quantity.